Color printer and multi-ribbon cartridge therefor

ABSTRACT

A color printer includes a print head assembly including a plurality of independently actuable print heads serially arranged along a printing direction. Each print head includes a plurality of impact pins and an associated different color printing ribbon having a portion disposed between the associated print head and a media to be printed upon. The serial alignment of the print heads enables four color images to be produced by a single pass of the print head assembly along the media in a printing direction. Control apparatus includes pulse modulation circuitry for controlling the impact force of each impact pin to cause intensity modulation of printed colored marks. In addition, a feedback system enables the control apparatus to vary the impact force of each impact pin to maintain good color fidelity. An ink ribbon cartridge includes a plurality of compartments with each compartment having a ribbon supply area and an associated pathway for passage of a ribbon loop exterior to the compartments, said ribbon loops being disposed in a line along a front face of the cartridge frame. Drive apparatus circulates each ribbon from the supply over to the pathways and back into the supply area during which time each ribbon is rotated 180° about a longitudinal axis thereon.

This application is a division of application Ser. No. 133,889, filed3/25/80, now U.S. Pat. No. 4,403,874.

BACKGROUND OF THE INVENTION

The present invention relates generally to the field of printers andmore particularly to the field of color impact printers for producingcolor characters and images from video type signals or data processingcomputer output.

Printers for use in the data processing field commonly are either inkjet or impact types, each type having particular advantages anddisadvantages. Ink jet printer "spray" a stream of fine ink dropletstowards a printing media and form ink dot printing patterns thereon bydeflecting the airborne ink droplets with an electric field.

A serious disadvantage of ink jet printers is the difficulty inachieving reliable operation. Because of the required small size of theink droplets, the ink jets and associated capillary passage ways areeasily clogged. In addition, the flow of ink in such printers is verysensitive to ambient temperature and humidity, as well as to shock andvibration. Ink jet printers also typically require use of specialprinting media formulated to be compatible with the characteristics ofthe ink used to prevent excessive ink droplet smearing or ink diffusioninto the media.

Color ink jet printers having several independently controlled ink jets,each of a different color, have recently been made commerciallyavailable, although at substantial cost. Such printers ordinarilyachieve full color printing from the several (usually four) ink jets soclosely together at each printing position that the human eye perceivesonly a single color combination of the different deposited droplets.Alternatively, partial or complete ink droplet overlaying techniques maybe used to obtain the desired color combination at each print spot.

Although being capable of providing printing in good color directly fromelectronically formatted information, multi-jet color ink jet printershave severe problems. This is principally because the heretoforementioned problems associated with ink jet printers typically multiplyas ink jets are added for full color printing. As a consequence, ink jetcolor printers tend to be relatively unreliable, requiring frequent andexpensive maintenance in order to maintain good color quality. Theseproblems, as well as high initial costs, generally limit usefulness ofcurrently available ink jet color printers to those relatively fewapplications in which printing costs are relatively unimportant.

Since ink jet color printers are generally not practical in low costapplications or those in which ambient conditions cannot easily becontrolled, a substantial need exists for alternative types of colorprinters.

Impact printers which use rotatable balls or "daisy wheels" to print anentire alphanumeric character or symbol with a single printing strokesuch as typewriters and the like, are capable of good quality printedtext necessary for most printed communication purposes, at moderatespeeds. However, such printers are of little practical value forproducing computer graphics as is frequently necessary. Additionally,mechanical complexity causes such printers to be relatively expensive topurchase and maintain.

A less common type impact printer utilizes ball point pens which aredriven against a print media. This type of printer is also usuallyunreliable because of ink flow interruptions and overflow. And, sincerolling contact is normally required to transfer ink from the pen ontothe printing media, such printers are limited to line drawingapplications.

Impact printers having an array of closely spaced, individually actuableimpact printing pins, on the other hand are relatively inexpensive highspeed printers. Selectively actuating different printing pins in thearray, enables the forming of virtually any alphanumeric character orsymbol. Although such pin matrix printers, which print the desiredcharacters and symbols as a series of unconnected dots or line segmentsdo not provide the printed word quality of ball or "daisy wheel" impactprinters, they are much more versatile than whole character printers,since "dot" matrix printouts of charts, graphs and images are enabled.This is a substantial advantage for data processing and video signalapplications in which the desired visually reproduced output is requiredto be in other than text form.

Typically, color impact printers have used a single impact print head,and a single printing ribbon having several different transverse orlongitudinal colored ink zones. After a first printing "pass" on eithera line-by-line or page-by-page basis, in which a first colored ink zoneof the ribbon is positioned between the print head and the printingmedia, a second colored ink zone of the ribbon is positioned between thehead and media. A second printing "pass" is then made, the procedurebeing repeated until all the colors (ordinarily four) necessary to printin full color print have been printed.

Various problems are also associated with this type of color impactprinting. For example, since multiple printing passes are necessary, theprinting rate is relatively slow and registration of the sequentialprinting impacts at each printing point is difficult to achieve andmaintain, particularly for other than line-by-line printing.

A further substantial problem is color contamination of various inkzones, particularly of light color areas of the printing ribbon by usingonly a single print head for printing all the different colors. Thus,after the ribbon has been used only a short time, and before the inksupply on the ribbon has been depleted, printing color fidelity issignificantly reduced. This effect is particularly disadvantageous inthose applications, such as geophysical or topographical mapping, inwhich the printing colors represent important information color.

Even without color contamination, inked ribbons must be replacedperiodically because of ink depletion. Since such ink depletion isgradual, color impact printers may produce faded or distorted colorreproduction during a length of time preceding replacement, and becauseof the often difficult and messy task of replacing spool held ribbon,replacement is typically deferred until the print quality is quite poor.

SUMMARY OF THE INVENTION

As a result of these and other problems with data processing-type colorprinters, applicants have invented a four color impact-type printerwhich uses several separate print heads, each one of which hasassociated therewith a separate colored ink ribbon. Since each printhead contacts only its associated ink ribbon, print head contaminationof the ribbons is eliminated. Further, ribbon color contamination, isminimized by arranging the print heads to print the colors in order ofincreasing darker hues.

In addition, the print head impact force is controlled in order to varythe intensity of each color to enable a full spectrum of colors to beprinted. Also, through the use of a feedback network, the colorintensity can be monitored and adjusted to accommodate for ink depletionin the ribbons.

To facilitate ribbon replacement as well as reduce the size and weightof the print heads, a multi-ribbon cartridge, or cassette, is provided.By incorporating all the inked ribbons into a single cartridge,structure that may be necessary for the support of separate singleribbon cartridges is eliminated, thus reducing the weight associatedwith the print head. Since rapid start and stop movement of the printheads may be necessary, such weight reduction is desirable to increaseprinter response and speed. In addition, with a single multi-ribboncartridge, the print heads may be spaced close together therebyfacilitating alignment of the print heads with each other. Suchalignment is important in achieving high resolution print output.

In accordance with the present invention, an impact printer forproducing color characters and drawings on a media includes a print headassembly including a plurality of independently actuable impact printheads serially arranged along a printing direction. Each print head hasa different color printing ribbon associated therewith and each ribbonhas a portion disposed between the associated print head and the media.By serially aligning the print heads along a printing direction, onlyone pass across the media is necessary to print a four color image ordrawing. This significantly increases the printing speed by eliminatingmultiple passes of the print head past the media as is necessary forconventional-type multicolor impact printers.

In addition, means for causing relative movement between the print headassembly and the media along the printing direction and means for movingthe ribbon past the associated print head are provided.

In order for each of the serially arranged print heads to sequentiallymark the media at preselected positions, index means is provided andcontrol means is provided for selectively actuating the print heads ateach preselected position along the printing direction in a mannercausing a preselected color combination mark thereon.

In an exemplary embodiment of the invention, means, disposed on theprint head assembly, are provided for supporting a removable cartridge,having a plurality of different colored inked ribbons, in an operativerelationship with the print head assembly. When the cartridge is inoperative relationship with the print head assembly each separate ribbonis disposed between an associated print head and the media.

Each of the print heads includes solenoid actuable pin means forstriking the associated ribbon against the media and the control meansinclude pulse modulation means for controlling the impact force of eachprint head pin means to cause intensity modulation of the colored marks.In addition, the control means includes means responsive to a colorsignal for varying the impact force of each print head pin means inorder to maintain color intensity and feedback means are provided formonitoring intensity of preselected color marks and generating a colorsignal corresponding thereto.

The feedback means are operative to enable the control means to vary theimpact force of the heads in a manner corresponding to the colorintensity of printed marks, higher impact force producing colors ofgreater intensity. Thus it is apparent that as the inks are depletedfrom the individual ribbons, the control means is able to increase theimpact force to maintain good color fidelity.

An ink ribbon cartridge, or cassette, is provided which includes a frameand means, disposed within the frame, for defining a plurality ofcompartments with each compartment having a ribbon supply area and anassociated pathway for passage of a ribbon loop exterior to eachcompartment. The pathways are spaced apart and serially arranged tocause the ribbon loop exterior to the compartments to be disposed in aline along a front face of the frame. A plurality of separate differentcolored continuous ribbons are provided, with each ribbon being disposedin an associated compartment ribbon supply area and having a loopportion extending through the associated pathway.

Drive means are provided within the cartridge for circulating eachribbon from the supply area to the pathway and back into the supplyarea. The drive means is configured for engagement with an externaldrive capstan. In an exemplary embodiment of the cartridge, each ribbonsupply area and associated pathway are spaced apart to enable a printhead to be disposed therebetween. In addition, means are provided forcausing each ribbon to rotate 180° about a longitudinal axis thereon asthe ribbon is moved from the supply area to the associated open pathway.In this manner, the ribbon life is increased because both sides of theribbon are utilized and continually reversed to permit marking from bothsides of the ribbon.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features and advantages of the present inventionwill appear from the following description when considered in connectionwith the accompanying drawing, in which:

FIG. 1 is a diagram, partially in block form, of the impact printergenerally showing a controller, an indexer and a print head assembly;also shown, although not part of present invention, are a signal sourceand an interface coupled between the signal source and the impactprinter;

FIG. 2 is a perspective view of the print head assembly and a four colorribbon cartridge in an operative relationship therewith and generallyshowing four independently actuable impact print heads serially arrangedalong a printing direction, apparatus for moving the print head assemblyrelative to a printing media along the printing direction, and apparatusfor moving the media in a media advancing direction;

FIG. 3 is a cross sectional view of the print head assembly and thecartridge showing the cartridge in an operative relationship with theprint head assembly and apparatus for circulating the ribbons within thecartridge and ribbon loop portions past associated print heads;

FIG. 4a is an enlarged cross sectional view of a print head generallyshowing nine independently actuable impact pins and solenoids forcausing movement of the impact pins;

FIGS. 4b and 4c, taken together, show the alignment of the impact pinswith respect to the printing media and the paths followed by the impactpins along the media as the print head assembly is moved across themedia in a printing direction;

FIGS. 5 and 6, taken together, are a schematic diagram of a pulsemodulator for controlling the impact force of each print head impact pinto cause intensity modulation of colored mark formed on the media, andgenerally showing individual pulse generators used for each impact pin,only three of the identical generators being shown for clarity ofpresentation; and

FIG. 7 is a perspective view of the four color cartridge partiallybroken away and exploded to more clearly show internal features of thecartridge which include drive apparatus, ribbon supply areas and spacedapart pathways serially arranged to enable passage of the ribbon loopsalong a front face of the cartridge.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Turning now to FIG. 1, there is shown in diagram form, an impact printer10 in accordance with the present invention, which generally includes acontroller 12, an indexer 14 and a printer mechanism 16 including aprint head assembly 18, having four print heads 24, 26, 28, 30, forproducing colored marks on a printing media 32 which may be, forexample, common paper, fabric, or plastic.

Also shown in FIG. 1, are a number of signal sources 40 from which theimpact printer 10 may receive information to be displayed in characterand/or graphic form. These signal sources 40 may include, for example, atelevision receiver 42, a video camera 44, a video tape/disc recorder 46or a computer 48.

Interconnected between the signal sources 40 and the impact printer 10is an interface 52. The interface 52, which is not part of the presentinvention, may be of any type suitable for accepting signals from thesignal sources 40 and generating corresponding input signals to thecontroller 12 which are compatible therewith.

The controller 12 generally includes a line digitizer 54 with datastorage capability, color assignment circuitry 56, a pulse modulator 58and comparator 60. The line digitzer 54 may be a state of the artanalog-to-digital convertor for receiving a video type signal andproducing a digital signal corresponding thereto. As will besubsequently discussed in greater detail, the controller 12 functions toselectively actuate the print heads 24, 26, 28, 30, at preselectedpositions along a printing direction, X (FIG. 1) in a manner causing apreselected colored combination mark on the media 32. The pulsemodulator 58 is operative for controlling the impact force of each printhead 24, 26, 28, 30, to cause intensity modulation of the colored marks.

Output from the controller 12 is received by the indexer 14 whichgenerally includes print head drivers 66, 68, 70, 72, for driving eachof the print heads 24, 26, 28, 30, respectively; delay circuits 78, 80,82; a media, or paper, driver 84; and a print head assembly driver 86.As will be hereinafter discussed in greater detail, the indexer 14 isoperative for driving the print head assembly 18 and the media 32, in acoordinated manner to index each print head 24, 26, 28, 30, thusenabling the controller 12 to sequentially mark the media 32 with eachprint head 24, 26, 28, 30 at preselected positions.

Also shown in FIG. 1 are a media, or paper, drive mechanism 92responsive to the driver 84, a print head assembly drive mechanism 94responsive to the assembly driver 86, and a ribbon drive mechanism 96interconnected with a ribbon cartridge, or cassette, 98 for moving inkedribbons 100, 102, 104, 106, (FIG. 2) past the print heads 24, 26, 28,30, respectively.

As more clearly shown in FIG. 2, the print head assembly 18 generallyincludes the four print heads 24, 26, 28, 30, interconnected by a frame110 with said print heads 24, 26, 28, 30 being serially arranged along aprinting direction X.

As hereinbefore mentioned, the utilization of a unitary four ribboncartridge 98 may enable the print heads 24, 26, 28, 30, to be disposedin closer proximity with one another by the frame 110. It is apparentthat such close spacing between the print heads 24, 26, 28, 30, mayenable exact alignment of the print heads 24, 26, 28, 30 along theprinting direction, X, in order that the print heads 24, 26, 28, 30 mayprecisely impact the media 32 at the same preselected positions thusenabling production of quality color printing with high resolution.

Each ribbon 100, 102, 104, 106, is inked with a selected different colorand has a loop portion, disposed between the associated print heads 24,26, 28, 30, and the media 32. In FIG. 7, the loop portions 112 and 114are illustratively shown for ribbons 104 and 106 respectively.

Disposed on the print head assembly 18 is a color sensitive photo cell124, or the like, for monitoring the intensity of preselected colormarks and generating a color quality signal corresponding thereto whichis directed to the comparator and digitizer 60 by a feedback line 126(FIG. 1). As will be discussed subsequently in greater detail, thecontroller 12, via the comparator and digitizer 60 and the pulsemodulator 58, is responsive to the color signal for varying the impactforce for each print head 24, 26, 28, 30, in order to maintain colorintensity.

The print head assembly 18 is slidably mounted on support rods 136, 138,by means of a guide 140 and a bearing 142, respectively, fixed to theframe 110. The rods 136, 138, are in turn supported by members 144, 146,respectively, fixed to a suitable printer base 148.

Movement of the print head assembly 18 is enabled by a helical-type gearassembly 149, or the like, including a helical gear 150 disposed betweenthe members 146 and engaging the print head frame 110 in a conventionalmanner, bidirectional movement being caused by the assembly drive motorand gear assembly 94.

As previously mentioned, movement in the direction of the Arrow X is ina printing direction. By selecting the ribbons 100, 102, 104, 106, to beinked the colors yellow, magenta, cyan and black, respectively, theprinting sequence along the printing direction X is from light to darkhues thereby reducing the amount of color contamination which may occurbecause of repeated striking of preselected positions by differentcolored ribbons as a color combination mark is made.

After each printing pass across the media 32, the assembly 18 isreturned to a side 154 of the media 32 and the media 32 is advancedalong a media advancing direction Y by the drive motor 92 which may becoupled therewith by conventional paper transport apparatus 156, (FIG.3) which may include a drive belt 158, media engaging drive wheels 160and a suitable platen 162 disposed adjacent the print head assembly 18for supporting the media 32. As is customary, a manual paper advanceapparatus 164 (FIG. 2) may be provided to be used as necessary.

The print heads 24, 26, 28, 30, are preferably nine pin print headscommercially available from Epsilon of America, Inc., of Torrance,Calif., or Victor Inc. of Chicago, Ill., (FIG. 4a). Each of the pins 166are individually actuable by means of a solenoid 168 and the pins 166are aligned along the direction Y (FIG. 4b). As shown in FIGS. 1, 2 and3, the print heads 24, 26, 28, 30, are serially arranged along theprinting direction X so that each of the pins 166 move along parallelpaths 169 (FIG. 4c). Because the pins 166 are aligned to move alongpaths 169 in the X direction, selective actuation of the pins 166 alongthe printing direction X enables each of the pins 166, along a path 169,to strike preselected positions 172. Combination of the preselectedpositions 172 enables the pins 166 to produce alphanumeric characters,for example, the letter E shown in FIG. 4c, or any image formable by adot combination. Overmarking, or overprinting, by each of four printheads 24, 26, 28, 30 through associated different color ribbons 100,102, 104, 106, at each preselected position 172, enables colorcombination marks to be produced.

Using a pin 166 diameter of approximately 0.014 inch and precisealignment of the print heads 24, 26, 28, 30, along the X direction, asmay be enabled by closely spaced print heads, the resolution of theprinter 10 may be approximately the same as the electron beam spread ona twelve inch color television receiver.

It is important that each of the print heads 24, 26, 28, 30, have aseparate printing ribbon 100, 102, 104, 106, respectively, associatedtherewith in order that each of the print heads 24, 26, 28, 30 strikesthe media 32 through a single ribbon 100, 102, 104 or 106. Thissubstantially reduces the possibility of contamination of each head 24,26, 28, 30 with different colors, and because each head 24, 26, 28, 30had its own ribbon 100, 102, 104, 106 respectively, the mechanicaltransport problems associated with utilizing multicolored ribbons, or aset of ribbons all drawn past all the heads 24, 26, 28, 30, iseliminated.

A remaining possible mode of contamination of the heads 24, 26, 28, 30with different color is the "picking up" of color from the media 32 asthe heads 24, 26, 28, 30 sequentially mark the same spot to cause colorcombination thereon.

To reduce this type of contamination, the printing sequence may be:yellow, magenta, cyan and black. This results from the knowledge thatyellow colors are most sensitive to contamination and black the least.

To further reduce contamination of the colors, it is preferable that theindividual dye solvents, or bases, be immiscible. The dyes may be ofanaline type and may be suspended or dissolved in glycol or oil solventsas is well known in the art and described, for example, in "Henley'sTwentieth Century Book of Formulas" published by Books Inc., 1968, or"Material and Printing Processes" published by Hastings House, 1973.

Referring again to FIG. 1, the line digitizer 54 operates in aconventional manner to produce a digital signal which corresponds to apoint-by-point analysis, or breakdown, of the input signal along a linewith each point, corresponding to a particular color. Coupled with theline digitizer 54 is color assignment circuitry 56, which may be astorage device well known in the art, for determining the hue andintensity of a particular color and assigning a "gray scale" intensitylevel to each color. The range of intensity may be, for example, sixteenlevels. In other words, the color assignment circuitry 56 functions toassign for each color a value from zero to fifteen pending upon theintensity of the color desired for transmission to the pulse modulator58.

The color assignment circuitry 56 may also function in other modes ofoperation such as, for example, modifying the actual inputted color inorder to change the hue of any particular color as inputted by one ofthe signal sources 40, or, alternatively, producing false colors inorder to display, in color, inputted black and white information. Inthis latter mode of operation, a color rendition may be reproduced bythe printer mechanism 16 in accordance with a preselected assignment ofselected colors to the "gray scale" level of the inputted signal. All ofthese functions are well known in the art.

The intensity level in accordance with the color assignment circuitry 56is inputted to the pulse modulator 58 which in turn produces a signalproportional to the intensity of impact required by the print heads 24,26, 28, 30 in order to produce a preselect color intensity for each ofthe preselected colors.

The pulse modulator 58 functions to control the energy delivered to eachof the individual print heads 24, 26, 28, 30, through the associatedprint head drivers 66, 68, 70, 72, respectively, and may do so bycontrolling either the voltage, the current, or the duration of anelectrical pulse for actuating each of the print head solenoids 168.

Preferably the pulse modulator 58 controls the energy by varying theduration of the electrical pulse, or pulse width, transmitted to each ofthe print head solenoids 168. A circuit diagram of the pulse modulator58 is shown in FIGS. 5 and 6. Since each impact pin 166 (FIGS. 4a, 4b)of the print heads 24, 26, 28 and 30 is actuated by a separate solenoid168, a separate pulse modulator circuit for each solenoid 168 ispreferred. Hence, it is important that such circuitry be relativelysimple and inexpensive in order to provide dependable and economicaloperation of the printer 10. As shown in FIG. 5, for one exemplarycolor, the pulse modulator 58 may include nine pulse generators 178 eachincluding a digital-to-analog (D/A), convertor 180 which may consist ofa number of resistors 182.

It should be appreciated that for clarity of presentation, FIG. 5 showspulse width generators 178 for one of the color print heads 24, 26, 28,30 only, and only three of nine pulse width generators 178 necessary forthe nine pins 166 are shown. Each D/A convertor 180 may beinterconnected with a comparator 184 which may be of a commerciallyavailable type LM339. Associated with comparator 184 is resistor R₈.

Also connected with each comparator 184 through a line 188 is a rampgenerator 190, (FIG. 6), for providing a ramp waveform 192. The rampgenerator 190 provides a separate output, 188, 194, 196, or 198, foreach pulse width generator 178. As indicated on the ramp waveform 192,(FIG. 5), the voltage of the ramp may vary from +1 volt to ±12 volts.The dashed lines 200 superimposed on the ramp waveform 192 represent thevoltage output of the D/A convertors 180. The pulse output 222 isprovided by an output stage comprising resistors R₉, R₁₀, and R₁₁,transistor Q₁, diode D₁ and capacitor C₃.

The ramp generator 190 includes a "one shot" device 204 which may be ofa type 556 (approximately 250 microseconds) having associated circuitryincluding resistors R₁ and RV₁ and a capacitor C₁, interconnectedthrough a buffer 205 and resistor R₃ as shown in FIG. 6 with a pair ofoperational amplifiers (Op-amps) 206, 208 of type LM348 and transistor212 which may be of type 2N3904 or 2N3906. Associated with op-amp 206are resistors R₄ and R₅. Associated with op-amp 208 are resistors R₆,RV₂ and R₇, and capacitor C₂. The output of the Op-amp 208 is in turnfed into one input 207 of Op-amps 214, 216, 218, 220, each havingoutputs 188, 194, 196, 198, respectively, corresponding to the printheads 24, 26, 28, 30, having inked ribbons 100, 102, 104, 106 of thecolors, yellow, magenta, cyan and black, respectively, associatedtherewith. Fed to the other input 209 of op-amps 214, 216, 218, and 220are, respectively, the enable yellow, magenta, cyan and black enablesignals, via NAND gate 211 and inverter 213.

For clarity of presentation, the purpose and function of each and everycomponent as included in the drawing are not specifically enumeratedbut, are presented with sufficient identification as to component typeand interconnection to enable any person skilled in the art to bothunderstand and recreate the electronic system as therein presented.

In operation, the ramp generator 190 (FIG. 6) produces a ramp signal orwaveform 192 at the output of the Op-amps 214, 216, 218, 220. TheOp-amps 214, 216, 218, 220, operate to disenable the pulse generator 178fed individual solenoids 168 if the particular color is not to beoperated for a particular color imprint, the output of the Op-amps 214,216, 218, 220, being fed to the comparators 184 via the lines 188, 194,196, 198. The signal from the D to A convertor 180 corresponding tocolor intensity as determined by the color look up table in circuitry 56and the line digitizer 54 is compared with the ramp signal or waveform192 resulting in a pulse output 222 to each of the solenoids 168 whichhas a width dependent upon color intensity. The pulse width variationmay be from approximately 300 to approximately 550 microseconds.

As hereinbefore mentioned, if the particular color is not required, thepulse is disenabled so as to conserve power and the output of the pulsemodulator 58 stays along a zero line 228.

Returning now to FIG. 1, the indexer 14 generally includes the printhead drivers 66, 68, 70, 72, and a paper driver 84 and a print headassembly driver 86.

As the module head assembly 18 is driven across the paper 32 by theassembly motor 94, the print head drivers 66, 68, 70, 72 which includesa series of power drive transistors (not shown) are operative foractuating each of the pins 166 of each print head 24, 26, 28, 30 inresponse to the control pulses 222 from the pulse modulator 58. Theprint head assembly 18 may be moved at approximately 16 inches persecond and the controller 12, through the indexer 14, may operate toproduce approximately 60 dots per inch along the paper 32 in theprinting, of X, direction.

As is typical with conventional print head operation, solenoid actuationfor a period of 600 microseconds (i.e., a drive pulse 222 having a widthof 600 microseconds) produces a paper contact of approximately 200microseconds, the difference in pulse duration and impact duration beingcaused by electromechanical response time.

Delay circuitry 78, 80, 82 enables each printing head 24, 26, 28, 30 tosequentially mark the paper 32 at preselected positions along theprinting direction X. The delay circuitry 78, 80, 82, may be ofconventional design for delaying the electrical control pulses 222 fromthe pulse modulator 58 for a preselected period of time. Since, theprint head assembly 18 moves across the media 32 at a constant speed,the delay of the pulses 222 to the print heads 26, 28, 30, having theink ribbon colors of magenta, cyan and black associated therewith may beindexed to print on the same spot as a preceding print head 24, 26, 28,respectively.

In other words, since the print head assembly 18 may be moved across themedia 32 in the direction indicated by the Arrow X and the print heads24, 26, 28, 30, may be separated by approximately 160 dots, a delay ofapproximately 160 dots caused by the delay circuitry 78 interconnectedbetween the pulse modulator 58 and the print head driver 66 causes themagenta color to be printed on the yellow color as the assembly 18 ismoved across the paper 32. Similarly, the delays of 320 dots and 480dots provided by the delay 80, 82, enable cyan and black colors to besimilarly printed on the same position as the print head assembly 18 ismoved across the paper 32.

As previously mentioned, the photo-type cell, or sensor, 124 fixed tothe print head assembly 18 operates to monitor the color intensity ofcolored marks produced by the printer 10 on the media 32 and generate acolor signal corresponding thereto.

The colored marks monitored may be either a "control" pattern producedby the printer 10 from a self generated or separate "control" input, orthe colored marks monitored may be part of an output as produced by theprinter 10 corresponding to an input received from the signal source 40.

Line 126 and the comparator and digitizer 60 provides a feedback of thecolor signal to the pulse modulator 58 in order to maintain and controlcolor intensity of the marks. The comparator and digitizer 60 may be ofconventional design and include a digitizer in order to modify the colorsignal from the photo cell 124 into a corresponding modified signal thatcan be compared with the color intensity level as produced by the colorlook up table in color assignment circuitry 56.

The comparator and digitizer 60 operates to compare the modified colorsignal corresponding to the photo cell 124 output for a selected coloredmark, with the intensity level assigned by the color look up table incolor assignment circuitry 56 for the selected mark and to increase ordecrease the intensity level inputted to the modulator 58 for subsequentmarks in order to maintain consistent color intensity of the printer 10output.

Turning now to FIG. 7 there is shown, in greater detail, the four ribboncartridge 98 for disposing the ribbons 100, 102, 104, 106, between theassociated print heads 24, 26, 28, 30, when the cartridge 98 is placedin an operative relationship with the print head assembly 18, thecartridge 98 being shown partially broken away and the ribbons 100, 102,removed in order to better show the internal configuration of thecartridge 98.

Generally, the cartridge 98 includes an external frame 240 with a top242, bottom 244 and sidewalls 246 and a number of upstanding interiorwalls 252 extending from the top 242 to the bottom 244 and defining aplurality of compartments 260, 262, 264, 268.

The compartments 260, 262, 264, 268, are each divided into a ribbonsupply area 280 and an associated pathway 290 for enabling passage ofthe respective ribbon loop portions, such as loop portions 112 and 114exterior to each compartment 260, 262, 264, 268. The pathways 290 arespaced apart and serially arranged to cause the ribbon loops such asribbon loops 112 and 114, exterior to the compartments 260, 262, 264,268, to be disposed along a line 296 along a front face 300 of thecartridge frame 240. As shown in FIG. 7, each compartment 260, 262, 264,268 includes drive apparatus 302, having a power hub 304, an idler 306,and a stripper 308, the power hub 304 being configured for engagementwith a drive capstan 310 on the print head assembly 18 as best shown inFIG. 3. The capstan 310 may be driven by a bevel-type planetary gear 320engaging a similar mating gear 322 fixed to a drive shaft 324 coupled tothe ribbon drive motor 96. It should be appreciated that each of thedrive capstans 310 is similarly driven by a planetary gear, not shown,coupled to the drive shaft 324 in order that the motor 96 (FIG. 2)drives all of the ribbons 100, 102, 104, 106 by the shaft 324 (FIG. 3).

Turning again to FIG. 7, the idler 306 is supported by a yoke 330 andbiased against the power hub 304 by a spring 332 in order that the powerhub 304 has sufficient pressure against the associated ribbon 100, 102,104 or 106, to circulate the associated ribbon 100, 102, 104, or 106within the respective compartments 260, 262, 264, 268 and the pathways290.

To prevent the ribbons 100, 102, 104, 106 which are bunched into thesupply areas 280, from guiding around the power hub 304 and the idler306, and possibly jamming the ribbon movement in the cartridge 98, thestripper 308 includes an arm 338 positioned adjacent the power hub 304to guide the ribbons 100, 102, 104, 106, and prevent any wrapping of theribbons 100, 102, 104, 106 about the hub 304. In addition, an idlerstripper 340 may be provided to similarly prevent guiding of the ribbons100, 102, 104, 106, about the idler 306.

As shown in FIG. 7, the stripper 308 is supported within thecompartments 260, 262, 264, and 268 by a molded receptacle 342 formed inthe frame bottom 244 within each compartment 260, 262, 264, 268. Thepower hubs 304 and the yokes 330 are positioned and held within thecompartments 260, 262, 264, 268 by means of holes 350 and slots 352,respectively, cut into the cartridge top 242 and bottom 244, the slot352 enabling sliding movement of the yoke 330 therein to enable thespring 332 to move the yoke 330 and bias the idler 306 against the power304.

The inked ribbons 100, 102, 104, 106, may be conventional 1/2 inch widenylon, or the like, ribbon as typically used in printing apparatus andmay be inked with subtractive-type dyes of the colors, yellow, magenta,cyan and black, respectively, as hereinabove discussed.

Each ribbon 100, 102, 104, 106, is continuous and may be formed from aflat strip of 4 mil. woven nylon material having approximately 250threads per inch and a length as determined by the size of supply area280, or as determined by the amount of relative use of each color ribbon100, 102, 104, 106 in a specific color printing application.

To extend the useful printing life of each ribbon 100, 102, 104, 106, aMobius strip may be formed from a nylon rectangular strip (not shown) byturning one end thereon 180 degrees about a longitudinal axis thereonand attaching it to the other end as is well known. To facilitate the180 degree turning of the ribbon 100, 102, 104, 106, as it is circulatedfrom the ribbon supply area 280, through the pathway 290 and back to thesupply area 280, a guide member 360 is provided in each compartment 260,262, 624, and 268 to lead the ribbon 100, 102, 104, and 106 from thesupply area 280 into the pathway 290. An end 362 of the guide member 360frictionally engages the ribbon 100, 102, 104, 106 and creates tensionin the ribbon 100, 102, 104, and 106 between the guide end 362 and thepower hub 304, to enable the ribbon 100, 102, 104, and 106 to rotate180° between the guide end 362 and an opening 368 within a pathway orchannel 290 between the guide member 360 and the wall 252 and thepathway 290 communicating therewith. In addition, a spring member 370may be provided to create greater tension in the ribbons 100, 102, 104,106, by urging the ribbons 100, 102, 104, and 106 against the guide end362.

In order to properly position the cartridge 98 on the print headassembly 18, a number of positioning pins 381 (FIG. 3) are providedwhich engage mating recesses 382 in the print head assembly frame 110.Additionally, a set of magnetic members 384 are received into cartridgebottom openings 386 which are positioned over the frame 110 in order tomore firmly hold the cartridge 98 in position on the print assembly 18.

Although there has been described hereinabove a particular arrangementof an impact printer and multi-ribbon cartridge for the purpose ofillustrating the manner in which the invention may be used to advantage,it should be appreciated that the invention is not limited thereto.Accordingly, any and all modifications, variations or equivalentarrangements which may occur to those skilled in the art, should beconsidered to be within the scope of the invention as defined in theappended claims.

What is claimed is:
 1. An ink ribbon cartridge comprising:(a) a frame;(b) means disposed within the frame for defining a plurality ofcompartments, each compartment having a ribbon supply area and anassociated open pathway for passage of a ribbon loop, said pathwaysbeing spaced apart and serially arranged along a front face of theframe; (c) a plurality of separate different colored continuous ribbons,each ribbon being disposed in an associated compartment ribbon supplyarea and having a loop portion extending through the associated pathway;and, (d) drive means disposed within the cartridge for circulating eachribbon from the supply area through the pathway and back into the supplyarea, said drive means being configured for engagement with an externaldrive capstan.
 2. An ink ribbon cartridge comprising:(a) a frame; (b)means disposed within the frame for defining a plurality ofcompartments, each compartment having a ribbon supply area and anassociated pathway for enabling passage of a ribbon loop exterior toeach compartment, said pathways being spaced apart and serially arrangedto enable passage of the ribbon loop along a front face of the frame,said ribbon loops exterior to each compartment being spaced apart fromeach supply area to enable a printing head to be disposed therebetween;(c) a plurality of separate different colored continuous ribbons, eachribbon being disposed in an associated compartment ribbon supply areaand having a loop portion extending through the associated pathway; and,(d) drive means disposed within the cartridge for circulating eachribbon from the supply area, said drive means being configured forengagement with an external drive capstan.
 3. The ink ribbon cartridgeof claim 2 further including means for causing each ribbon to rotate180° about a longitudinal axis thereon as the ribbon is circulated. 4.The ink ribbon cartridge of claim 2 further including means for causingeach ribbon to rotate 180° about a longitudinal axis thereon as theribbon is moved from the ribbon supply area to the associated openpathway.
 5. The ink ribbon cartridge of claim 2 further including meansfor causing each ribbon to form a Mobius strip.
 6. An ink ribboncartridge comprising:(a) a frame; (b) means disposed within the framefor defining a plurality of compartments, each compartment having aribbon supply area and an associated pathway for enabling passage of aribbon loop exterior to each compartment, said pathways being spacedapart and arranged to cause the ribbon loops exterior to thecompartments to be disposed in a line along a front face of the frame;(c) a plurality of separate different colored continuous loop inkedribbons, each ribbon being disposed in an associated compartment ribbonsupply area and having a loop portion extending through the associatedpathway; (d) drive means disposed within the cartridge and engaging eachribbon adjacent one side of each open pathway for pulling each ribbonthrough the pathway and into the supply area, said drive means beingconfigured for engagement with an external drive capstan; and, (e) meansfor causing 180° rotation of each ribbon about a longitudinal axisthereon as the ribbon is moved from the ribbon supply area to anotherside of the associated open pathway.